Hand held internal combustion engine-driven, rotary cutters and trimmers have become very popular gardening and maintenance tools. It is customary for the internal combustion engine to be placed at the proximal end of the tool, with a boom projecting from it to the distal end where a working head is mounted for rotation. The working head is usually coupled to the engine by a flexible drive shaft which passes through the boom.
Fractional horsepower gasoline engines used in these tools generally drive the working head through a centrifugal clutch which is intended to release when the engine speed is reduced to idle, and when the engine is stopped. Occasionally there may be some frictional effects in the clutch which will cause some rotation at idle. This is undesirable and can be prevented by this invention.
However, a more important consideration is the continued rotation of the working head, and especially of a heavy cutter blade as the consequence of its inertia. The working head is driven at a high speed through a low-weight cable drive. When the clutch disengages, the working head will continue to rotate unless means is provided to stop it. This invention provides such a means.
It is an object of this invention to provide a brake system which will prevent rotation of the working head either by voluntary application of the brake system, or by involuntary application wherein the brake system is activated unless released by a voluntary action of the operator such as by holding the tool in a prescribed manner.